1. Field of the Invention
The invention relates generally to electrical switching apparatus and, more particularly, to trip bars for electrical switching apparatus, such as circuit breakers.
2. Background Information
Electrical switching apparatus, such as circuit breakers, as well as transfer switches, network protectors and the like, are often equipped with accessories such as, for example and without limitation, auxiliary switches, shunt trip devices, under voltage release devices, and bell alarms. Such devices can be employed in a variety of ways to provide signals indicating certain conditions within the apparatus and/or to initiate a change in status of the apparatus such as, for example, to trip open the separable contacts of the apparatus in response to an electrical fault condition (e.g., without limitation, current overload; short circuit; abnormal voltage).
In view of the increasing market trend to reduce the overall size of the circuit breaker, the space which is available within the circuit breaker housing is limited. In addition to size constraints, the location available for mounting accessories within the circuit breaker can also be problematic. For example, some locations for mounting the accessories in the circuit breaker have limited access for installing the accessories and, in some instances, blind installation is required, wherein it is not possible to see the accessory to mount the accessory within the circuit breaker housing. As a result, incorrect installation and/or damage to the accessories can result, and safety features of the circuit breaker can be adversely affected.
Additionally, some accessories such as, for example, some under voltage release (UVR) devices include an actuator, such as a stem. The stem is movable from a retracted position to an extended position in which it is structured to engage and actuate (e.g., pivot) the trip bar of the circuit breaker operating mechanism in order to, for example, initiate a tripping operation of the circuit breaker in response to a trip condition. Typically, the UVR is installed within the circuit breaker in a de-energized (e.g., no input voltage) state, in which the stem is disposed in the released (e.g., fully extended) position. This can make installation of the UVR difficult as the fully extended stem tends to interfere with the trip bar. It, therefore, becomes necessary to pivot the trip bar and/or depress the stem and hold it in the retracted position in order to properly install the UVR. This operation, which is typically performed by hand, is particularly difficult in view of the aforementioned limited access and space available within the circuit breaker to perform the installation.
There is, therefore, room for improvement in electrical switching apparatus, such as circuit breakers, and in trip bars therefor.